The purpose of this proposal is to investigate biochemical and immunochemical differences between the life cycle/developmental stages (promastigote - amastigote) of the parasite, Leishmania as these may provide important targets for both chemotherapeutic or vaccine approaches for the control of this disease. This proposal will focus primarily on the antigens/molecules specifically associated with the amastigote stage of Leishmania, to investigate their potential in induction of protective immunity and biological function. Specifically the aims of this proposal are: 1. Biochemical and biological characterization of stage-specific antigens (promastigote and amastigote) of Leishmania. The focus of these studies will be membrane components of the amastigote and flagellar components of the promastigote. 2. Development of methods/strains for the axenic (extracellular) culture of Leishmania amastigotes. 3. Identification and evaluation ( in vivo) of amastigote antigens protective against an infection with Leishmania sp.. 4. Molecular biological studies of stage-specific and protective antigens. Specifically, genes encoding for specific amastigote membrane proteins of L. pifanoi and L. amazonensis and Leishmania flagellar proteins will be studied. If time permits, other genes may be studied.